Poison
by Madcap Junior
Summary: Sherlock and John are engaged, and while their relationship is a little rocky it's ultimately just fine, right? Is new lab assistant Mary Morstan all that she seems, and is Sherlock right not to trust her? (Awful summary, I promise you it's nothing like it sounds...)


Domestic bliss; it was a phrase Sherlock apparently despised and certainly one he seemed incapable of actually putting into practice. Nonetheless John wouldn't change what they had for the world, despite the fact that in the three years they'd been together (after the three years that Sherlock had been "dead") they'd had countless rows, usually over petty things, but more recently they'd become more about Sherlock not telling John what was going on and what he was up to. One particularly bad row had ended with Sherlock upping and leaving in the middle of the night, leaving only a note by way of explanation-and even that only said "Sorry" and was therefore not entirely helpful.

After a few days of hiding out at Molly's she'd eventually slapped some sense into him-quite literally, since the fall she'd become a lot bolder around him-and he'd come back home, and after a lot of grovelling John had forgiven him yet again. It wasn't that Sherlock intended to hurt John, it was more that he didn't understand he was doing it and then got annoyed when John was angry for no apparent reason, according to him. But on top of all that the two did love each other and they were still engaged and very much intending to get married, all John needed to do now was continue training Sherlock and things would be idyllic. Getting him to throw out that gangrenous foot would be a good start-

"Cup of tea, John?" John looked up, snatched from his thoughts by the sudden question.

"Ah, no, thanks," he responded, smiling at Mary, one of the new lab assistants at Bart's.

"Wasn't expecting to see you here again-third night this week, isn't it?"

"Yeah…Sherlock's got a case-serial killer, you know how he gets," John shrugged dismissively.

"Sure I can't tempt you with that cuppa?" Mary asked again, "Or maybe a caffeine fix?"

John glanced over at Sherlock, who was charging around the morgue, attempting to examine two bodies at once while poor Molly tried to keep up with him, he looked back to Mary before nodding, "Okay, coffee, why not?"

Mary beamed at him, "Great, it doesn't look like I'm going to be able to get any work done with Sherlock here and it'll be nice to have some company."

John chuckled as they walked down to the canteen, "I know what it's like to be stuck waiting for Sherlock to be done, don't you worry about that."

Fifteen minutes later and the two were sat at one of the canteen's plastic tables, nursing spectacularly awful lukewarm coffee, John offloading everything that bothered him about Sherlock, "It's not that I'm asking for miracles, I just wish I didn't come downstairs every morning and end up having breakfast with some body part or another-there is actually a gangrenous foot just sitting on the table at the moment-I don't even think he's experimenting on it, I'm beginning to wonder if he just likes the colour-" John cut off when he realised he'd been talking solidly for a good five minutes, "Sorry…I'm rambling on a little bit, I very much doubt you want to hear all of this."

Mary shook her head, smiling reassuringly at him, "No, no, it's fine, it's good to get stuff like that off your chest every now and then, and I don't mind listening."

John finished his coffee, shrugging, "I guess, it's not really important anyway, I still love the stupid git," he smiled fondly at the mention of his fiancé and could have sworn that a scowl flickered over Mary's face, but it was so brief he actually doubted it had happened. Nonetheless he decided he probably should be getting back to the morgue, "Thanks, Mary, I'll see you around," he said non-committedly, heading back in the opposite direction.

John was amazed to discover that Sherlock had actually realised he'd gone, greeting him with, "Why have you been drinking bad coffee in the canteen?" John rolled his eyes, Sherlock didn't even need a minute to deduce what he'd been doing these days, however John no longer felt obliged to discuss his deductions, he simply ignored him and offered Molly a warm smile, "Thanks for all your help, we'll be leaving now-sorry for taking up yet another of your evenings, hope he wasn't too much trouble," he rattled off his usual apologies before grabbing Sherlock's hand and dragging him out of the morgue, something that had become almost a habit of his of late.

Back at 221B Sherlock and John were sat in their respective chairs, as per every evening, "What _were_ you doing having coffee in the canteen?" Sherlock asked again, apparently having not let it go.

"The new lab assistant-Mary-asked me to," John shrugged.

Sherlock frowned, "You were having coffee…with a girl?"

"It was hardly a date, Sherlock, just bad hospital coffee and a chat," he assured him, "We were both just waiting around and it was something to do."

Sherlock's frown didn't waver, "I don't trust her, her eyes are too bright when she looks at you," he declared.

John laughed quietly, shaking his head, "Now you're just being paranoid, she's nice-and you might want to make an effort with her, Sherlock, with Molly cutting down on her workload you'll be wanting her to let you have access to the morgue."

Sherlock somehow managed to frown deeper still, "I still don't see why Molly thinks that's necessary," he muttered.

John ignored it, getting up out of his chair, "I'm going to bed, coming?" When Sherlock shook his head John simply went ahead and got into bed without him, thinking over what he'd said. _Her eyes are too bright when she looks at me? That's ridiculous, _he chuckled again, _I swear he's getting even more possessive. _John sighed, rolling over and promptly falling asleep.

**And that's the first chapter! You have no idea how hard it was to get this started, I have the whole thing planned out but starting it was near impossible. Anyways, is Sherlock right not to trust Mary? Who knows, after all it was just one cup of bad coffee, right? **


End file.
